Datasheet

GD0
REFRTN
Q1
GND
RISNS1
RISNS2
RISNS6
GND
GND
Q2
Q6
GD1
SE0
LM3463
SE1
SE5
GD5
RIADJ2
RIADJ1
VREF
IOUTADJ
GND
GND
CVREF
LM3463
SNVS807A –MAY 2012–REVISED MAY 2013 www.ti.com
Figure 22. Individual connections to REFRTN
REFRTN and GND
The REFRTN pin is the reference point for the high precision and low noise internal circuits. The pins which
referenced to the REFRTN are VREF, IOUTADJ, SE0, SE1, SE2, SE3, SE4 and SE5. To secure accurate
current regulations, the current sensing resistors, R
ISNSn
should connect to the REFRTN pin directly using
dedicated connections. And the REFRTN and GND pins should be connected together using dedicated
connection as shown in Figure 22.
Device Enable
The LM3463 can be disabled by pulling the EN pin to ground. The EN pin is pulled up by an internal weak-pull-
up circuit, thus the LM3463 is enabled by default. Pulling the EN pin to ground will reset all fault status. A system
restart will be undertaken when the EN pin is released from pulling low.
Open Circuit of LED String(s)
When a LED string is disconnected, the LM3463 pulls the Faultb low to indicate a fault condition. The Faultb is
an open-drain output pin. An open circuit of a LED string is detected when a V
SEn
is below 43 mV and the V
DRn
of the corresponding channel is below 300mV simultaneously. When the fault conditions are fulfilled, the LM3463
waits for a delay time to recognize whether there is a disconnected LED or not. If the conditions of open circuit of
LED is sustained longer than the delay time, a real fault is recognized. The delay time for fault recognition is
defined by the value of an external capacitor, C
FLT
, and governed by the following equation:
(4)
The fault indication can be reset by either applying a falling edge to the EN pin or performing a system re-
powering.
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